[Help] After replace Nouveau for Nvidia, system doesn't start X

Hi. I've tried to replace nouveau for nvidia, to test performance. I've installed nvidia and nvidia-utils. Also removed nouveau-dri, xf86-video-nouveau and its libs and followed every https://wiki.archlinux.org/index.php/NV … au_drivers single step. After installing nvidia driver, I ran nvidia-xconfig to configure /etc/X11/xorg.conf automatically, then rebooted. For my surprise, arch didn't pass that black screen with bad screen resolution, which show mounting status. I had to boot with ubuntu livecd and use chroot to remove nvidia config lines in /etc/X11/xorg.conf file to make system work again. Any ideas about how can I install these drivers without doing a new clean arch installation?

Also World of Warcraft is very very laggy with nouveau and Perfect World is not running.